The Israeli military says the killing of the Hamas military chief in Gaza marks the beginning of a broader operation targeting Gaza militants.
Prime Minister Benjamin Netanyahu said Israel was prepared to expand its operation against Hamas targets in Gaza.
Ahmed al-Jaabari, who ran the armed wing of the radical Islamic movement, died along with a passenger after their car was targeted by an Israeli missile on November 14.
In a statement, Israel's Shin Bet domestic intelligence service confirmed Jaabari's death, citing his "decade-long terrorist activity."
He was the most senior Hamas official to be killed since an Israeli invasion of the Hamas-controlled Palestinian territory four years ago.
The Izz el-Din al-Qassam Brigades, Hamas's armed wing, said Jaabari's killing had "opened the gates of hell" and vowed harsh retaliation
Jaabari has long topped Israel's list of most wanted militants.
His killing comes after the latest surge of violence along the Gaza border.
At least five more Palestinians were reported killed in a wave of air strikes in Hamas-controlled Palestinian enclave later on November 14, while militants in response fired rockets into Israel.
Egypt's president has summoned the Israeli ambassador in Cairo to protest the air strikes.
A spokesman for President Muhammad Morsi said the president also decided to recall Egypt's ambassador to Israel.
UN Secretary-General Ban Ki-moon called on both sides to prevent an escalation of hostilities.
Israel used the tactic of targeted attacks against top militants during a wave of suicide bombings against Israel a decade ago.
Based on reporting by AP, AFP, and Reuters